Natural vs. lab-grown vs. moissanite: a neutral comparison.

1. What each one actually is

Natural and lab-grown diamonds are the same material with different origin stories. Moissanite is a different material altogether, chemically, optically, and on the Mohs hardness scale.

For graded jewellery in 2026, both natural and lab-grown diamonds are reported by GIA, IGI and other major laboratories on the same 4C scale (cut, colour, clarity, carat). Lab-grown reports explicitly disclose the laboratory-grown origin and the growth method (CVD or HPHT).

2. How they compare visually

At a viewing-room table, under loupe and microscope:

• Natural and lab-grown diamonds are visually identical. No naked-eye test distinguishes them. Trained gemmologists use DiamondView, FTIR or photoluminescence spectroscopy to identify the growth signatures, but a loupe alone cannot.
• Moissanite shows visibly more "fire", rainbow-coloured flashes, because its refractive index (~2.65) is higher than diamond's (2.42). This is sometimes a feature, sometimes a tell, depending on aesthetic preference.
• Moissanite is also doubly refractive. Looking through the table at the pavilion facets at the right angle shows visible doubling of the facet edges. Diamond is singly refractive and never shows this.
• On the Mohs hardness scale, diamond is 10 (the reference), moissanite is 9.25, and other simulants (cubic zirconia, white sapphire) are 8.5 or lower. All three of these (natural, lab-grown, moissanite) are durable enough for daily wear over decades.

3. How prices have moved (2020 to 2026)

The most consequential market story of the past five years is the price collapse in lab-grown diamonds. As CVD and HPHT production capacity scaled (most aggressively in China and India) wholesale lab-grown prices have fallen approximately 70-90% from 2020 to 2025.

Figures are working trade estimates from polished-trade services and SA cutting-house intake records, rounded for clarity. Specific stones move with grade nuance and timing. Treat as direction, not an exact quote.

In retail, the same dynamic plays out one or two layers downstream. A 1.00 ct lab-grown G-VS1 ring that retailed in 2020 at the equivalent of R 80,000-100,000 commonly retails today at R 18,000-30,000 for the same grade and setting. Natural-diamond retail has not moved similarly.

Moissanite has held a relatively stable 1.00 ct equivalent retail of roughly R 4,000-12,000 across that window, because its production base was already mature and its market is its own.

4. The resale curve over twenty years

Resale is where the segments diverge most sharply. A twenty-year-old GIA-Excellent natural diamond bought from a reputable house typically resells, today, at 30-60% of its original retail price, discounted, but on a real secondary market with real buyers. The Rapaport list still applies. A cutting house, a tender, or a specialist buy-back desk will give a real price.

A twenty-year-old lab-grown stone has no comparable resale market today, and the production-side curve suggests the 2026 stone will resell in 2046 at a small fraction of even its now-discounted retail. Most retail jewellers refuse lab-grown trade-ins outright; the few that accept them usually offer melt-equivalent or lab-grown-replacement-cost terms.

Moissanite is not a resaleable jewellery asset. Buy-back offers are essentially zero. The buyer is purchasing the stone and the setting, not a stake in the secondary market.

Resale is not the only metric, but it is the metric that most aligns "what you paid" with "what someone else is willing to pay later". For a buyer who treats the stone as a wearable asset over decades, the curve matters. For a buyer who treats it as one-time apparel, it does not.

5. Ethics, sustainability, and the Kimberley Process

Lab-grown marketing leans heavily on an ethics narrative. The reality is more layered and more interesting than the slogans on either side suggest. The thumbnail:

• The 1990s "blood diamond" concerns drove the Kimberley Process Certification Scheme, which has substantially reduced the share of conflict rough in international trade.
• Formal-sector producers operating under multi-stakeholder best-practice frameworks (De Beers, Rio Tinto, Petra Diamonds, BHP and others operating outside the current sanctions regime) document chain-of-custody from mine to rough invoice. Rough sourced through this system is end-to-end traceable in ways the small-scale alluvial sector still is not. Russian-origin rough (the largest single source by volume historically) is excluded under UK and US sanctions; Prodiam does not source it.
• Lab-grown production is energy-intensive, most production uses grid electricity in countries with predominantly fossil-fuel mixes. The carbon footprint of CVD/HPHT diamonds is comparable to mined diamonds on a per-stone basis, and the renewable-only claims that some retailers make should be treated as marketing unless there is an on-site PPA or comparable evidence.
• South African beneficiation under the Diamonds Act 1986 adds a layer above and beyond the Kimberley Process: it mandates in-country cutting, majority-SA-citizen ownership, and explicit local-economic-uplift conditions for licensed manufacturers. See the SA beneficiation explainer.

Honest answer: both segments have legitimate sustainability work to do. Neither has a clean monopoly on ethics. The documentation a buyer should ask for, regardless of segment, is provenance, the chain from origin to till, not a slogan.

6. Which one fits which buyer

7. Where Prodiam stands

Prodiam is a natural-diamond-only house. Every stone we cut, polish, certify and sell is a natural diamond, on a GIA or EGL report, polished at our Bedfordview bench. We do not stock or sell lab-grown stones, moissanite, or any simulant.

That choice is structural, not a judgement of other segments. Our business is built around the De Beers DBCM Emerging Beneficiation Customer relationship, the SA Diamonds Act manufacturing licence, the Procut DCW cutting bench, and the long-term value curve of natural diamonds. A lab-grown stone is a different product for a different buyer with a different goal.

If the right answer for you is a lab-grown or moissanite stone, we will say so directly and recommend a specialist. If the right answer is a natural diamond, we are the cutting house in the country with the shortest chain between rough and your finger.

Frequently asked questions